Acoustic phonon dynamics in strained cubic and hexagonal GaN/Al2O3 superlatticesP. D. Sesion, E. L. Albuquerque, M. S. Vasconcelos, P. W. Mauriz and V. N. FreireEur. Phys. J. B, 51 4 (2006) 583-591DOI: https://doi.org/10.1140/epjb/e2006-00256-0